1. Field of the Invention
The present invention relates to an automatic tool changer for a lathe or the like.
2. Prior Art
There are available a variety of devices which provides for selectability of any one of a plurality of tools for operating on a workpiece, for use on lathes and the like. In many of these devices a plurality of tools are carried by a rotating turret supported on the cross slide so that they can be rotated to bring into an active position any one of the tools fixedly secured to the turret. Strictly speaking, this type of device is not a tool changing apparatus in the sense of the present invention, since all of the tools are fixed to the turret and the turret is merely rotated to bring a desired tool into the active position.
However, one type of actual tool changing machine provides a tool magazine at a fixed location on the main stationary frame of the lathe for storing a plurality of tools which can be exchanged with an active tool on the cross slide where a tool is positioned for working on the workpiece. Such devices generally require the cross slide to be moved to a position adjacent the magazine during the transfer of the tools between the magazine and the cross slide, and thus work on the workpiece must be stopped for a substantial period of time to permit this operation to occur.
Still further such equipment provides for a magazine for storing a plurality of tools, to be secured to the cross slide for movement therewith, and also provides for some means of transferring the tools from the magazine to the active position on the cross slide adjacent the workpiece. This latter type of tool changing apparatus is of the general type to which the present invention more closely relates. However, there have been difficulties and disadvantages associated with this type of tool changing equipment in the past. For example, one difficulty is that since the magazine and the transfer apparatus are maintained in close relation to the active position for operation on the workpiece, they are generally prone to contamination in the operating parts of the equipment due to metal chips from the workpiece, and from the coolant used during the cutting operation. This condition can result in difficulties in maintaining the proper alignment of the active tool in the work position due to such contaminant material becoming lodged between the mounting surfaces for the tool holder on the cross slide, which then causes misalignment of the tool with respect to the workpiece, and consequently introduces error into the machining operation.
A further difficulty associated with this latter type of device is that the magazine is mounted to the carriage at a remote location from the workpiece, possibly to reduce the above referred to difficulty. The cross slide must then be moved a substantial distance away from the workpiece to a position adjacent the magazine in order to reduce the above referred to difficulty. The cross slide must then be moved a substantial distance away from the workpiece to a position adjacent the magazine in order to effect exchange of the tool from the active position, or tool post, on the cross slide to the magazine and vice versa. The cross slide must then be returned to the working position for operation on the workpiece by the newly selected tool, all of which takes a substantial period of time.